Dunn experimental program impoverished is to flatter”^11 ), Heatley was
essential. No one in the world knew how to successfully grow Penicillium,
and it was going to take creativity, stubbornness, keen insight, and luck.
Heatley—humble, elegant, tall, and slender—did not waste time in
deciphering the ideal conditions for Penicillium cultivation.
The life cycle of Penicillium came into clear view in 1939. The
Penicillium culture would grow a thin white carpet over the agar, and as it
matured, the branchlike mycelia would grow and generate penicillin-rich
droplets that yellowed as they dried. These droplets could be harvested
with a pipette, but harvesting too early limited the yield; waiting too long
oversaturated the fungus, and further growth was squelched.
The mold grew adequately on agar, but precious little “mold juice” was
produced without extra nutritive substances. Heatley turned to different
growing containers and altered the temperature. Fertilization with nitrates,
salts, sugars, glycerol, and meat extracts, combined with enriching the air
with oxygen and CO 2 , was performed. Brewer’s yeast was added, and
when one reads of Heatley’s maneuverings you are left questioning
whether he felt more like a chef, horticulturist, brewer, or scientist.
Adding urgency to the effort was Hitler’s invasion of Poland on
September 1, 1939. Chain could no longer travel back to Germany, and,
unable to rescue his mother and sister, both perished in Nazi concentration
camps. Great Britain and France declared war on Germany within days of
the invasion, further heightening the urgency of the penicillin production
and testing. Refinement of the growing process and the expansion of
penicillin production continued into 1940, but no testing of the finished
product had been performed.
On March 19, 1940, the first suitable batch of penicillin was finally
processed and tested for stability. Chain, as the expert chemist, set to work
on determining what type of molecule penicillin was. Primitive testing
conditions notwithstanding, to Chain’s great surprise, the molecule was
not a protein, but what it was was not immediately obvious. The first step
in clinical analysis was to inject two mice in the abdomen with the entire
amount of collected penicillin. To the team’s great relief, the mice
tolerated the injections without incident and more amazingly, excreted it
in their urine, unaltered.
Production of penicillin continued, and within two months, on May 25,
1940, an experiment with groups of infected mice was carried out at